Color temperature can be described in terms of the color emitted by a light fixture with a spectrum from bright light, such as daylight, to warm soothing amber light such as at dusk. LED light sources do not exhibit visible spectrum radiation at all wave lengths of the spectrum and are measured according to a correlated color temperature (CCT) scale. It would be desirable for a user person to be able to control the brightness of individual sets of LED chips with the sets having different correlated color temperature from each other, to produce by the combination of the sets of LED chips, a desired light environment which is warm, cozy, relaxing or bright such as is desirable during dinning or working late over a desk top or in front of a computer or simply creating a bright environment in a working area. It is well known that bright light stimulates the senses of a person and can be disruptive to a person's health particularly when exposed to bright light at night time creating the effect of jet lag, poor sleep and lack of energy during the day. It could also lead to other adverse conditions such as disruption of vital hormone production. It is therefore desirable to provide a means to a user person to be able to control LED light sources to modify the environmental light to suit a specific period of time.
The unit of measure of color temperature of LED's is K for Kelvin, which is defined as the color temperature of an absolute blackbody when it is heated to a certain temperature and the radiation color of an LED light source is the same as that of an absolute blackbody. Different color temperatures will create different environments, such as when the color temperature is below 3000K, the light is red, giving people a warm and stable feeling. Suitable for household use, and which renders objects more colorful, is a color temperature higher than 5000K wherein the light color is blue, giving a sense of refreshment. Studies have shown, as mentioned above, that lower color temperatures can make people more likely to enter a resting state, while higher color temperatures can improve people's concentration.
The color temperature of LED fixtures and LED bulb devices having two sets of LED's of different CCT (correlated color temperature) can be adjusted to create a desirable light atmosphere. For current market products, users will use switch devices on LED fixtures and lamps to select the color temperature they need. The advantage of this method is that it can limit the inventory of having to stock several types of LED sets of different Kelvin color temperature, but the main disadvantage is that the color temperature needed by users must be selected before the installation of the light sources or fixtures, which is a great inconvenience.
As mentioned above, the brightness of LED sources and LED fixtures can be adjusted by adjusting a switch device on the fixture. It is known to use dimmer switches to adjust brightness of LED light sources. Dimmer switches are generally based on the principle of the use of silicon control rectifier chopper circuits. By adjusting the control button of the dimmer switch, the silicon control rectifier dimmer changes the energy transmitted to the LED, and its brightness output changes. Such dimmer control can only control and adjust the brightness.
There is a need to provide a new control device similar to a dimmer switch, which is installed on a wall or elsewhere or packaged differently for remote control and which can permit a user person to select a specific color LED or Led set and to change the color temperature and brightness of LED's, either directly on a wall control unit or remotely by a wireless control device with the signal transmitted by the control device and analyzed at any time by the circuitry controlling the color temperature and brightness to effect a color LED selection and establish a link to control the brightness thereof.
It is therefore a feature of the present invention to provide a system and a method which permits a user person to control an LED light source, having two or more color LED's or LED sets of different CCT, by permitting the user person to modify the color temperature and brightness of each of the LED's or LED sets in an LED light source by the use of a mechanical switch or a wireless electronic control switching means to produce a desired light environment.
Another feature of the present invention is to provide a system and a method to permit a user person to independently adjust the color temperature and brightness of two or more color LED's or LED sets in an LED light source, each having different correlated color temperatures (CCT) to create a desired light atmosphere in an environment and wherein the adjustment can be stored in a memory of a microcomputer.
A further feature of the present invention is to provide a system and method utilizing a novel system and circuit design to permit a user person to select a desired color LED or LED set mounted in an LED light source having two or more color LED's or LED sets of different correlated color temperatures and to control the brightness of a selected color LED or LED set and to repeat the control of the other color LED and also adjust the correlated color temperature thereof to create a desired light atmosphere by combining the two or more color LED's or LED sets by different CCT adjustments.
A still further feature of the present invention is to provide a novel control command signal by converting a section of the waveform of the supply voltage to include a specific number of half cycle binary code identifying a selected one of the LED's or LED sets of different CCT.
According to the above features, and from a broad aspect of the present invention, there is provided a system for independently adjusting the correlated color temperature (CCT) and brightness of a light source having two or more color LED's each having a different correlated color temperature. The system comprises signal conversion means for transmitting a command waveform containing a binary code representative of a control signal identifying a selected one of the two or more color LED's or LED sets as selected by a user person to enable the selected one of the two or more LED's or LED sets to receive a dimming brightness signal for brightness adjustment to create a desired light atmosphere in an environment lit by the adjustment of the brightness of each of the two or more color LED's or LED sets
According to a further broad aspect of the present invention the selection of a color LED of the two or more color LED's or LED sets is effected by generating a control command waveform signal by modifying the supply voltage waveform by chopping selected half wave periods in a predetermined consecutive number of zero crossing intervals to generate a binary code signal including a control command binary code representative of a selected one of the two or more color LED's or LED sets to enable the selected one of the LED's to be controlled for adjusting its brightness.
According to a still further broad aspect of the present invention there is provided a method of independently adjusting the correlated color temperature (CCT) and brightness of a selected on of two or more color LED's or LED sets with each of the LED's or LED sets of an LED light source having a different correlated color temperature. The method generally comprises the following steps of:    (i) selecting by a control device one of the two or more color LED's or LED sets having a predetermined correlated color temperature and transmitting a selection signal representative thereof to signal conversion circuit means,    (ii) converting a power supply voltage waveform to produce a command waveform signal including a binary signal representative of the selection signal,    (iii) enabling the selected one of the two or more LED's or LED sets,    (iv) controlling by a further control device the brightness of the selected one of the two or more color LED's or LED sets by producing a dimming signal to adjust the brightness of the enabled selected one of the two or more color LED's or LED sets to create a desired light atmosphere in an environment lit by the two or more color LED's or LED sets and adjusting the brightness thereof, and    (v) repeating said steps (i) to (iv) for selecting a further of the two or more color LED's or LED sets and adjusting the brightness thereof.
According to a further broad aspect of the present invention the method provides automatically enabling a signal transmitting circuit having a controller receiving a signal at a first input thereof to instruct a signal conversion circuit to produce a located between a start bit and a stop bit of the binary signal for feeding a signal analyser to effect the step (iii). The transmitting circuit has a second input for receiving a dimming signal for operating a driver circuit to adjust the brightness of the selected one of the two or more color LED's or LED sets.
According to a still further broad aspect of the invention, the signal conversion circuit is a chopper semiconductor circuit for adjusting the conduction delay time of the sine wave of a 120 volt, 60 cycle supply voltage to produce the composite command waveform signal having said command binary signal corresponding to a selected one of said two or more color LED's or LED sets. The composite command waveform signal is fed to a signal analyser circuit to permit identification and enabling of the selected one of the two or more color LED's or LED sets and to provide for the adjustment of the brightness of the selected one of said two or more color LED's or LED sets.